FILAMENTOUS SULFUR PRODUCTION AT OXIC-ANOXIC INTERFACES BY NOVEL SULFIDE OXIDIZERS ON A COSMOPOLITAN SCALE

We have recently described a chemoautotrophic, sulfide-oxidizing coastal marine microbe unique among Prokaroytes in that it excretes elemental sulfur in the form of long, irregular filaments. These microaerophilic, vibrioid microorganisms are retained in sulfidic, high-fluid flow environments by the production of mats of entangled filamentous sulfur. Through 16S rRNA sequencing the organism has been identified as an Arcobacter sp., tentatively named Candidatus Arcobacter sulfidicus. Based on recent observations, microbial filamentous sulfur formation occurs in a variety of sulfidic coastal environments, in deep-sea and shallow-water hydrothermal vent ecosystems worldwide. A shallow subsurface biosphere dominated by these sulfide oxidizers may be an important component heretofore unconsidered in the overall organic matter production at hydrothermal vents. The ubiquity of filamentous sulfur formation suggests that organisms phylogenetically related to Candidatus Arcobacter sulfidicus are likely to be present on a cosmopolitan scale. Comparative phylogenetic studies using specific oligonucleotide probes based on the 16S rRNA sequence in combination with methods to assess its in situ activities are used to provide information about its ecological role and the possible presence of geographically distinct populations.